Olives oil the Mediterranean diet

Olive oil is the most important dietary fat source of the Mediterranean diet. Since 4000 BC, olive oil has been obtained there, but it is now synonymous worldwide with health and gastronomic quality.1 Recent studies consistently support the Mediterranean diet as compatible with healthier ageing and longevity.

Olive oil improves the risk factors for cardiovascular disease, such as the lipoprotein profile, blood pressure, glucose metabolism and antithrombotic profile. Endothelial function, inflammation and oxidative stress are also positively modulated. 2 As a result, the US Food and Drug Administration recently announced the availability of a qualified health claim for mono-unsaturated fat from olive oil and reduced risk of coronary heart disease. An increasing number of scientific studies explain the contribution of olive oil to the prevention of human diseases.

The sum of its parts
Olive oil is characterised by a relatively low level of polyunsaturated essential fatty acids and by a high content of mono-unsaturated fatty acids (mainly oleic acid), which are able to lower both total and LDL cholesterol levels3 and can protect against age-related cognitive decline and Alzheimer’s disease.2

A mono-unsaturated fatty acid-rich diet, moreover, is a good alternative to high-carbohydrate diets for nutrition therapy of type 2 diabetes because, besides having a superior patient acceptance, it has similar effects on LDL oxidative resistance, on metabolic control and on the lipid profile.4

A recent study also showed the mechanism of a direct benefit of polyphenol-rich olive oil on endothelial function in humans.5 This is attributed to minor components of extra virgin olive oil — tocopherols, phenols, sterols, hydrocarbons and flavour compounds.

The major antioxidant of olive oil is alpha-tocopherol, the tocopherol with the highest vitamin E activity.6 It acts as an antioxidant, inhibiting the development of heart disease by reducing the oxygen-related damage along artery walls.3 Phenolic compounds, such as hydroxytyrosol, tyrosol, caffeic acid and vanillic acid, also have showed antioxidative and anti-inflammatory properties.7,8

The potential role of olive oil in cancer prevention, based on the numerous evidences referred to its components, has been recently reviewed.9 Among hydrocarbons, the major component, squalene, a precursor of sterol biosynthesis and a scavenger of reactive oxygen species, has been proposed as a causal factor for the low incidence of cancer in Mediterranean populations.2,10,11 Other hydrocarbons are also present, including the pro-vitamin A beta-carotene, albeit in small quantities.12

Phytosterols are bile acid sequestrants and their consumption leads to lower levels of plasma LDL cholesterol, and there are several reports on their anti-tumour effects, especially about beta-sitosterol, the main phytosterol of olive oil.13,14

Oleocanthal, a polyphenol whose pungency induces a stinging sensation in the throat, has been recently shown to exert non-steroidal anti-inflammatory activity due to its ability to inhibit the activity of cyclooxygenase enzymes (COX1 and COX2), a pharmacological action shared by ibuprofen.15 Finally, some benefits of olive oil in human diseases such as rheumatoid arthritis, diabetes mellitus and gastrointestinal pathologies have been recently reviewed.16

The richness of olive oil in healthy compounds may contribute to the prevention of a number of diseases and is a reason to recommend it as the main source of dietary fat.

1. Tur Mari JA. The quality of fat: olive oil. Arch Latinoam Nutr 2004;54:59-64.
2. Perez-Jimenez F. International conference on the healthy effect of virgin olive oil. Eur J Clin Invest 2005; 35:421-4.
3. Stark AH, et al. Olive oil as a functional food: epidemiology and nutritional approaches. Nutr Rev 2002; 60:170-6.
4. Rodriguez-Villar C, et al. Comparison of a high-carbohydrate and a high-monounsaturated fat, olive oil-rich diet on the susceptibility of LDL to oxidative modification in subjects with Type 2 diabetes mellitus. Diabet Med 2004; 21:142-9.
5. Ruano J, et al. Phenolic content of virgin olive oil improves ischemic reactive hyperemia in hypercholesterolemic patients. J Am Coll Cardiol 2005; 46:1864-8.
6. Bauernfeindz JC. Tocopherol in foods. In Vitamin E, a comprehensive treatise; Macchlin, L. J., Ed.; Marcel Dekker: New York, 1980; Vol I, p100-60.
7. Bonanome A, et al. Evidence of postprandial absorption of olive oil phenols in humans. Nutr Metab Cardiovasc Dis 2000; 10:111-20.
8. Petroni A, et al. Inhibition of leukocyte leukotriene B4 production by an olive oil-derived phenol identified by mass-spectrometry. Thromb.Res 1997; 87:315-22.
9. Owen RW, et al. Olives and olive oil in cancer prevention. Eur J Cancer Prev 2004; 13:319-26.
10. Cao CV, et al. Chemopreventive effect of squalene on colon cancer. Carcinogenesis 1998; 19:287-90.
11. Smith TJ, et al. Inhibition of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NKK)-induced lung tumorigenesis and DNA oxidation by dietary squalene. Proc Am Assoc Cancer Res 1999; 40:262.
12. Kiritsakis A, et al. Olive oil: a review. Adv Food Res 1987; 31:453-82.
13. Wilt TJ, et al. Beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review. BJU Int 1999; 83:976-83.
14. Awad AB, et al. Beta-sitosterol inhibits growth of HT-29 human colon cancer cells by activating the sphingomyelin cycle. Anticancer Res 1998; 18:471-3.
15. Beauchamp GK, et al. Ibuprofen-like activity in extra-virgin olive oil. Nature 2005; 437:45-6.
16. Zamora Ardoy MA, et al.Olive oil: influence and benefits on some pathologies. An Med Int 2004; 21:138-42.

Fabio Galvano and L La Fauci are on the faculty at Mediterranean University of Reggio Calabria, Italy.
G Galvano is at the University of Catania, Italy.
Respond: [email protected]

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